ISHS Acta Horticulturae 618: XXVI International Horticultural Congress: Environmental Stress and Horticulture Crops
RELATIONSHIP BETWEEN STOMATAL DENSITY AND IONIC LEAKAGE AS INDICATORS OF COLD HARDINESS IN OLIVE (OLEA EUROPAEA L.) |
| Authors: | A. Soleimani, H. Lessani, A. Talaie |
| Keywords: | Artificial freezing, Low temperature, Electrical conductivity, Winter injury, Freezing tolerance |
| Abstract:
Screening different cultivars of olive (Olea europaea L.) for cold hardiness is one of the major objectives in numerous breeding programs and research projects. Selection by stomatal density may be based on the fact that winter injury frequently results in desiccation of the plant tissues. In fact, plants repeatedly have great difficulty in absorbing water when the temperature drops below 0°C and this process may stop entirely if the soil freezes. Leaf samples of one-year-old olive cultivars including cvs. 'Koroneiki', 'Mission', 'Roghani' and 'Zard', were taken and exposed to cold temperatures at a rate of drop of 4°C per h to 0°C, -4°C, -8°C and-12°C. By electrolyte leakage studies the lethal freezing temperature (LT50) of cultivars was found and cultivars were grouped into hardy, Semi-hardy and non-hardy. The density of stomata in the leaves of cultivars rated as hardy were significantly lower than those cultivars rated as semi-hardy and non hardy. Stomatal density of the cultivars in the intermediate class fell within the range of hardy and non-hardy cultivars. The number of stomata may well constitute a simple and effective selection criterion for screening olive plants for cold hardiness especially in early stages of plant growth, for breeding programs. | |
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